1. Field of the Invention
This invention relates to intraosseous dental anesthesia, an apparatus for effecting such anesthesia, and a method for using such apparatus.
2. Statement of Related Art
Dental anesthesia is generally by a topical anesthesia injection followed by a deeper injection which blocks off the nerve endings within the region (infiltration) or blocks off the sensory nerves at some distance from the region (nerve blocking). It is extremely desirable to minimize the amount of anesthesia injected, since toxic reactions may result from drug sensitivity or misdirection of the injection needle into the bloodstream, which reactions may be so severe as to cause convulsions or cardiac or respiratory failure (see The Merck Manual, 13th ed., (1977) Merck & Co., Rahway, N.J. U.S.A. at 226). Moreover, misplacement of the hypodermic needle or even a slight error in placement may necessitate further injections, raising the risk of such toxic reactions. Furthermore, conventional anesthesia results in numbness of the tongue, cheek, and/or lips or even part of the face during the dental procedure and for some time afterward. This is very discomforting for the patient.
Ideally, an apparatus and/or method for dental anesthesia injection should have various positive attributes, including:
1. Almost immediate effectiveness (within one minute or less); PA1 2. Effectiveness for both maxillary (upper jaw) and mandibular (lower jaw) applications; PA1 3. Simplicity of application; PA1 4. Minimal special apparatus; PA1 5. Capability of utilizing various points of penetration; PA1 6. Capability of administration with minimal pressure, so as to avoid causing pain; PA1 7. Capability of administration outside of septic area; PA1 8. Minimal chance of injection into blood vessels; and PA1 9. Minimal post-operative effects. PA1 I. Injection into mucous tissue PA1 II. Injection into a ligament PA1 III. Injection into the septum PA1 IV. Injection near the nerve-trunk (nerve blocking)
Conventional methods of dental anesthesia, include the following.
A. Advantages: PA2 B. Disadvantages: PA2 A. Advantages: PA2 B. Disadvantages: PA2 A. Advantages: PA2 B. Disadvantages: PA2 A. Advantages: PA2 B. Disadvantages:
1. Ease of application; PA3 2. Injection possible with minimal pressure; PA3 3. Efficient for both maxillary and mandibular application; PA3 1. Too long before anesthesia takes effect (about 5 minutes); PA3 2. The amount of anesthesia is high (about 4 cc); PA3 3. Requires adrenalin or another vaso conductor, with cardiac patients; PA3 1. May be injected near the apex of the tooth; PA3 2. Is effective in about 1 minute; PA3 3. Efficient for both maxillary and mandibular application; PA3 1. Requires high pressure for injection, causing pain; PA3 2. Injection is into a septic area; PA3 3. Risk of infection of the ligament is increased; PA3 4. May increase post-operative problems, including inflammation and necrosia; PA3 1. Requires small amount of anesthesia (about 1 cc); PA3 2. Anesthetic effect is immediate (1 minute or less); PA3 3. Efficient for both maxillary and mandibular application; PA3 4. Minimal after effects (numbness); PA3 1. Injection requires strong pressure, making it very painful; PA3 2. Exact positioning of needle is required; PA3 3. Injection is into a septic area; PA3 1. Very effective; PA3 2. Avoids post-operative inflammation or infection; PA3 1. Long delay in effecting anesthesia (10 minutes or more); PA3 2. High risk of injection into a blood vessel, potentially dangerous to some patients; PA3 3. Post-operative numbness is very long lasting.
As can be seen from the above, none of the conventional methods for dental anesthesia is without serious disadvantages. The only remaining anesthetic method involving the local administration of an anesthesia for dental work, is intraosseous anesthesia (i.e. injection into the jawbone itself, as contrasted into soft tissue or into the ligament/septum).
Intraosseous dental anesthesia, when properly used, affords a profound numbness limited only to the tooth to be treated.
U.S. Pat. No. 2,317,648 -- Siqveland, discloses a particular apparatus for intraosseous dental anesthesia, and a method for its use. However, the disclosed apparatus is not in use today, although this patent was granted in 1943. In the Siqveland patent, a threaded sleeve is concentrically and removably positioned around a drill bit, shown as element 15 in FIG. 5. The drill bit 15 as illustrated is of conventional, solid, mechanical drill bit configuration. The drill bit 15 at its non-boring end is connected to a flange 17 which is itself connected to a shank 16 adapted to be connected to a contra-angle. The patent teaches away from the use of the drill bit 15 without the threaded sleeve 20 surrounding it. The combination drill bit/threaded sleeve penetrates the bone, and the drill bit is then detached and withdrawn, leaving the threaded sleeve embedded in the bone as a guide for a hypodermic needle. After injection of the anesthesia, the threaded sleeve is withdrawn from the bone by reverse rotation. A spring and gasket means is used to operate the parts simultaneously. Thus, the patented device comprises at least 3 separate elements, all of very small size, which must be connected and disconnected during its utilization. U.S. Pat. No. 2,317,648 also discloses as background information (page 1, lines 27-39) an "old" method which is called "intraosseous". However, the old method involves drilling a hole into the side of the tooth. This method is not intraosseous, since a tooth is not bone. The subject invention does not contemplate drilling into a tooth to effect anesthesia.